The binding of certain heavy metal ions, particularly CH3Hg(II), cis- and trans-(H3N)2Pt(II), and Ag(I) to nucleosides, and polynucleotides is being studied to determine the sites at which these ions bind, the extent of binding, and the effect of metal coordination on the conformation of the polynucleotides. In particular, differences between the antitumor agent cis-(H3N)2Pt(II) and its inactive isomer trans-(H3N)2Pt(II) are being sought. A highly sensitive, computer operated Raman difference spectrophotometer is being constructed around a double monochromator equipped with concave holographic gratings. A mode locked, cavity dumped dye laser is being constructed as an excitation source for time-resolved Raman spectroscopy in order to minimize interference from fluorescence of the samples. BIBLIOGRAPHIC REFERENCES: Heavy Metal-Nucleotide Interactions, Binding of Methylmercury(II) to Purine Nucleosides and Nucleotides Studied by Raman Difference Spectroscopy, S. Mansy and R. S. Tobias, J. Amer. Chem. Soc., 96, 6874 (1974). Heavy Metal-Nucleotide Interactions, The Participation of Amino Groups in the Binding of Methylmercury(II) to Cytidine and Adenosine-5'-Phosphate in Aqueous Solution: Studies by Raman Difference Spectrophotometry, S. Mansy, J. P. Frick, and R. S. Tobias, Biochim. Biophys. Acta, 378, 319 (1975).